Monday, September 29, 2014

In a world where there are plenty of sources for playoff odds that actually take into account the personnel currently available for each team, use projected rather than 2014-only performance, consider pitching matchups, and the like, there is no real reason for me to post this. Nonetheless, here are some very crude playoff odds. The key assumptions:

• Team strength is constant and is measured by my Crude Team Ratings, using an equal weight of W%, EW%, and PW% regressed with 69 games of .500
• Home field advantage is uniform and the home team wins 54.5% of the time

From there, the math is pretty simple and I will present with little explanation. First, the ratings which are used to feed the estimates:

These ratings don’t know or care that Oakland has stopped scoring runs (or that the magic influence of Cespedes is gone); they don’t know that Garret Richards is injured; they don’t know anything other than these team’s schedules, their wins and losses, runs and runs allowed, and BA/OBA/SLG and allowed.

From here, it’s just plug and chug. Wildcard game odds:

Home field offsets OAK’s perceived strength advantage over KC.

Division series:

Here, “P” is the probability that the series occurs; P(H win) is the probability that the home team wins should the series occur; and P(H) is the probability that the series occurs and that the home team wins [P*P(H win)].

LCS:

World Series:

The probability of one of the “rivalry” matchups (OAK/SF, LAA/LA, BAL/WAS, or KC/STL) occurring is 21.5%, which is not bad at all. LAA/LA is the second-most likely series; the least likely is KC/SF, which is good because that is the one that I would least like to see.

Putting it all together:

One might be surprised by OAK having better odds to win a Division Series and each subsequent round than KC even though the latter is favored in their wildcard game, but the ratings (perhaps incorrectly) think the A’s are one of the strongest teams in the playoffs, and thus the Royals wild card game edge, solely due to home field, is insufficiently large to keep them ahead. KC would need a rating of around 122 to have an equal World Series win probability to the A’s.

The odds suggest a 57.6% chance that the junior circuit wins it all, not a surprise given that the AL teams rank 1-2-3-6-7 in strength and they have home field in the World Series to boot. In fact, the AL is favored in 22 of 25 potential matchups, with the only exceptions being Washington against Detroit or Kansas City and Los Angeles against Kansas City.